The LHNCBC Medical Ontology Research project encompasses basic research on biomedical terminologies and ontologies and their applications to natural language processing, clinical decision support, translational medicine, data integration and interoperability. In the past few years, our research has focused on the integration, dissemination, quality assurance and applications of drug ontologies and on quality assurance in biomedical ontologies. We also develop application programming interfaces (APIs) and browsers for RxNorm and related drug resources.